Figure 8.

Conditioned fibers beyond the lesion still associate with NG2+ cells. Double conditioning lesion (2xCL) of the sciatic nerve allows several injured fibers to grow beyond the lesion center 21 d after SCI. a, GFAP expression (green) shows the glial scar surrounding the lesion. Vimentin (purple) is expressed within the lesion center and the penumbra. Arrows show fibers that have grown rostral to the lesion. a′, Dextran-Texas Red (DexTR)-labeled fibers from image a. The boxes illustrate select fiber endings at higher magnification. b, Higher magnification of the area near the asterisk in a′ from a serial slice, demonstrating that the majority of Dextran-Texas Red-labeled fibers remain caudal to the lesion in association with NG2+ cells. NG2 (green) expression is found in the lesion center and throughout the tissue. The brightness in a and b differ, so that NG2 expression could be visualized. SV2 expression is found accumulated in the endings of fibers caudal to the lesion but not those that have crossed rostrally. c, Fiber rostral to the lesion without SV2 (purple) expression. d, Fiber from b caudal to the lesion, with SV2 expression in its ending. e, Z-stack projection of a Dextran-Texas Red-labeled fiber found rostral to lesion core associated with NG2 expression. Scale bars: a,100 μm; b, 50 μm; c, d,10 μm; e, 20 μm.